Disease Severity and Cytokine Expression in the Rhinovirus-Induced First Wheezing Episode.

Wheezing children infected with rhinovirus (RV) have a markedly increased risk of subsequently developing recurrencies and asthma. No previous studies have assessed the association between cytokine response and the severity of acute illness in the first wheezing episode in children infected with RV. Forty-seven children treated both as inpatients and as outpatients infected with RV only, aged 3-23 months, with severe first wheezing episodes were recruited. During acute illness, peripheral blood mononuclear cells (PBMCs) were isolated and stimulated with anti-CD3/anti-CD28 in vitro. A multiplex ELISA was used to quantitatively identify 56 different cytokines. The mean age of the children was 17 months, 74% were males, 79% were hospitalized, and 33% were sensitized. In adjusted analyses, the inpatient group was characterized by decreased expressions of interferon gamma (IFN-γ), interleukin 10 (IL-10), macrophage inflammatory protein 1 alpha (MIP-1α), RANTES (CCL5), and tumor necrosis factor-alpha (TNF-α) and an increased expression of ENA-78 (CXCL5) compared to the outpatient group. The cytokine response profiles from the PBMCs were different between the inpatient and outpatient groups. Our results support that firmly controlled interplay between pro-inflammatory and anti-inflammatory responses are required during acute viral infection to absolve the initial infection leading, to less severe illness.

Maternal fish oil and/or probiotics intervention: Allergic diseases in children up to two years old.

BACKGROUND: As n-3 long-chain polyunsaturated fatty acids and probiotics possess immunomodulatory properties, theoretically they could lower the risk of allergic diseases. But their effects remain controversial. We aimed to study the effects of fish oil and probiotics separately or in combination from early pregnancy onwards to lower the risk of allergic diseases in the infants. METHODS: In this double-blind trial, women (n = 439) in early pregnancies were randomized into four intervention groups: fish oil + placebo, probiotics + placebo, fish oil + probiotics, and placebo + placebo. Fish oil (1.9 g docosahexaenoic acid and 0.22 g eicosapentaenoic acid) and probiotic (Lacticaseibacillus rhamnosus HN001 and Bifidobacterium animalis ssp. lactis 420, 1010 colony-forming units each) supplements were provided for daily consumption from randomization up to 6 months postpartum. All analyses were adjusted with pet ownership. RESULTS: No difference between the infants in the four intervention groups were found regarding physician-diagnosed food allergy, atopic eczema, or atopy at the age of 12 or 24 months (all p > .05). The probiotic intervention was associated with lower odds of recurrent wheezing at 24 months (OR 0.39, 95% CI 0.18-0.84, p = .017), but not at 12 months. CONCLUSIONS: The use of fish oil and/or probiotics from early pregnancy onwards did not lower the odds of childhood allergic diseases or atopy, with the exception of the probiotic intervention which decreased the risk of recurrent wheezing when the infants were two years old. This suggests that the incidence of asthma could also decrease later in childhood and thus these outcomes need to be clarified in further investigations.

Cytokine expression in rhinovirus- vs. respiratory syncytial virus-induced first wheezing episode and its relation to clinical course.

Rhinovirus (RV) and respiratory syncytial virus (RSV) are common causes of bronchiolitis. Unlike an RSV etiology, an RV etiology is associated with a markedly increased risk of asthma. We investigated the cytokine profiles of RV- and RSV-induced first wheezing episode and their correlation with prognosis. We recruited 52 sole RV- and 11 sole RSV-affected children with a severe first wheezing episode. Peripheral blood mononuclear cells (PBMCs) were isolated during acute illness and 2 weeks later and stimulated in vitro with anti-CD3/anti-CD28. Culture medium samples were analyzed for 56 different cytokines by multiplex ELISA. Recurrences were prospectively followed for 4 years. In adjusted analyses, the cytokine response from PBMCs in the RV group was characterized by decreased expression of interleukin 1 receptor antagonist (IL-1RA), interleukin 1 beta (IL-1ß), and monocyte chemoattractant protein-1 (MCP-1) and increased expression of eosinophil chemotactic protein 2 (eotaxin-2), thymus- and activation-regulated chemokine (TARC), and epithelial-derived neutrophil-activating peptide 78 (ENA-78) in the acute phase and increased expression of fractalkine in the convalescent phase compared to those in the RSV group. An analysis of the change in cytokine expression between study points revealed an increased expression of fractalkine and IL-1ß and decreased expression of I-309 (CCL1) and TARC in the RV group compared to those in the RSV group.. Considering hospitalization time, a significant non-adjusted group × cytokine interaction was observed in the levels of interferon gamma (IFN-γ), macrophage-derived chemokine (MDC), IL-1RA, and vascular endothelial growth factor (VEGF), indicating that a higher expression of cytokine was associated with shorter hospitalization time in the RSV group but not in the RV group. A significant interaction was also found in interleukin 6 (IL-6), but the cytokine response was not associated with hospitalization time in the RSV or RV group. In the RV group, increased expression of I-309 (CCL1) and TARC was associated with fewer relapses within 2 months, and decreased expression of interleukin 13 (IL-13) and increased expression of I-309 (CCL1) were associated with less relapses within 12 months. Differences in cytokine response from PBMCs were observed between RV- and RSV-induced first severe wheezing episode. Our findings also reveal new biomarkers for short- and medium-term prognosis in first-time wheezing children infected with RV or RSV.

Herpesvirus infections in adenoids in patients with chronic adenotonsillar disease.

Adenoids and tonsils have gained interest as a new in vivo model to study local immune functions and virus reservoirs. Especially herpesviruses are interesting because their prevalence and persistence in local lymphoid tissue are incompletely known. Our aim was to study herpesvirus and common respiratory virus infections in nonacutely ill adenotonsillar surgery patients. Adenoid and/or palatine tonsil tissue and nasopharyngeal aspirate (NPA) samples were collected from elective adenoidectomy (n = 45) and adenotonsillectomy (n = 44) patients (median age: 5, range: 1-20). Real-time polymerase chain reaction was used to detect 22 distinct viruses from collected samples. The overall prevalence of herpesviruses was 89% and respiratory viruses 94%. Human herpesviruses 6 (HHV6), 7 (HHV7), and Epstein-Barr virus (EBV) were found, respectively, in adenoids (33%, 26%, 25%), tonsils (45%, 52%, 23%), and NPA (46%, 38%, 25%). Copy numbers of the HHV6 and HHV7 genome were significantly higher in tonsils than in adenoids. Patients with intra-adenoid HHV6 were younger than those without. Detection rates of EBV and HHV7 showed agreement between corresponding sample types. This study shows that adenoid and tonsil tissues commonly harbor human herpes- and respiratory viruses, and it shows the differences in virus findings between sample types.

No Correlation Between Nasopharyngeal Human Bocavirus 1 Genome Load and mRNA Detection or Serology in Adeno-/Tonsillectomy Patients.

Human bocavirus 1 (HBoV1) can persist in nasopharynx and tonsils. Using HBoV1 serology, reverse-transcription polymerase chain reaction (PCR) for detecting messenger RNA (mRNA) and quantitative PCR for HBoV1 genome load count, we studied to what extent the HBoV1 DNA loads in nasopharynx correlate with acute infection markers. Tonsillar tissue, nasopharyngeal aspirate, and serum were obtained from 188 elective adeno-/tonsillectomy patients. Relatively high loads of HBoV1 DNA were detected in the nasopharynx of 14 (7%) primarily asymptomatic subjects with negative mRNA and/or serodiagnostic results. Quantitative HBoV1 DNA PCR may have lower specificity than HBoV1 mRNA detection for diagnosing symptomatic infection.

Tonsillar cytokine expression between patients with tonsillar hypertrophy and recurrent tonsillitis.

BACKGROUND: Tonsils provide an innovative in vivo model for investigating immune response to infections and allergens. However, data are scarce on the differences in tonsillar virus infections and immune responses between patients with tonsillar hypertrophy or recurrent tonsillitis. We investigated the differences in virus detection and T cell and interferon gene expression in patients undergoing tonsillectomy due to tonsillar hypertrophy or recurrent tonsillitis. METHODS: Tonsils of 89 surgical patients with tonsillar hypertrophy (n = 47) or recurrent tonsillitis (n = 42) were analysed. Patients were carefully characterized clinically. Standard questionnaire was used to asses preceding and allergy symptoms. Respiratory viruses were analysed in tonsils and nasopharynx by PCR. Quantitative real-time PCR was used to analyse intratonsillar gene expressions of IFN-α, IFN-ß, IFN-γ, IL-10, IL-13, IL-17, IL-28, IL-29, IL-37, TGF-ß, FOXP3, GATA3, RORC2 and Tbet. RESULTS: Median age of the subjects was 15 years (range 2-60). Patients with tonsillar hypertrophy were younger, smoked less often, had less pollen allergy and had more adenovirus, bocavirus-1, coronavirus and rhinovirus in nasopharynx (all P < 0.05). Only bocavirus-1 was more often detected in hypertrophic tonsils (P < 0.05). In age-adjusted analysis, tonsillar hypertrophy was associated with higher mRNA expressions of IL-37 (P < 0.05). CONCLUSIONS: Intratonsillar T cell and interferon gene expressions appeared to be relatively stable for both tonsillar hypertrophy and recurrent tonsillitis. Of the studied cytokines, only newly discovered anti-inflammatory cytokine IL-37, was independently associated with tonsillar hypertrophy showing slightly stronger anti-inflammatory response in these patients.

Contribution of repeated infections in asthma persistence from preschool to school age: Design and characteristics of the PreDicta cohort.

BACKGROUND: The PreDicta cohort was designed to prospectively evaluate wheeze/asthma persistence in preschoolers in association with viral/microbial exposures and immunological responses. We present the cohort design and demographic/disease characteristics and evaluate unsupervised and predefined phenotypic subgroups at inclusion. METHODS: PreDicta is a 2-year prospective study conducted in five European regions, including children 4-6 years with a diagnosis of asthma as cases and healthy age-matched controls. At baseline, detailed information on demographics, asthma and allergy-related disease activity, exposures, and lifestyle were recorded. Lung function, airway inflammation, and immune responses were also assessed. Power analysis confirmed that the cohort is adequate to answer the initial hypothesis. RESULTS: A total of 167 asthmatic children (102 males) and 66 healthy controls (30 males) were included. Groups were homogeneous in respect to most baseline characteristics, with the exception of male gender in cases (61%) and exposure to tobacco smoke. Comorbidities and number and duration of infections were significantly higher in asthmatics than controls. 55.7% of asthmatic children had at least one positive skin prick test to aeroallergens (controls: 33.3%, P = .002). Spirometric and exhaled nitric oxide values were within normal limits; only baseline FEV0.5 and FEV1 reversibility values were significantly different between groups. Viral infections were the most common triggers (89.2%) independent of severity, control, or atopy; however, overlapping phenotypes were also common. Severity and control clustered together in an unsupervised analysis, separating moderate from mild disease. CONCLUSIONS: The PreDicta cohort presented no differences in non-asthma related measures; however, it is well balanced regarding key phenotypic characteristics representative of "preschool asthma".

Relapse Among Infants Hospitalized for Bronchiolitis in Finland.

In a prospective cohort of children hospitalized for bronchiolitis, we examined the rate of and characteristics associated with bronchiolitis relapse. Bronchiolitis relapse was documented in 22 (6%) of 391 children, and median time to relapse was 2 (interquartile range, 1-7) days. Relapse occurred more often in males. Prenatal smoking and smoke exposure in the home were also associated with relapse.

Rhinovirus-induced first wheezing episode predicts atopic but not nonatopic asthma at school age.

BACKGROUND: Persistent childhood asthma is mainly atopy driven. However, limited data exist on the risk factors for childhood asthma phenotypes. OBJECTIVE: We sought to identify risk factors at the first severe wheezing episode for current asthma 7 years later and separately for atopic and nonatopic asthma. METHODS: One hundred twenty-seven steroid-naive children with the first severe wheezing episode (90% hospitalized/10% emergency department treated) were followed for 7 years. The primary outcome was current asthma at age 8 years, which was also analyzed separately as atopic and nonatopic asthma. Risk factors, including sensitization, viral cause, and other main asthma risk factors, were analyzed. RESULTS: At study entry, median age was 11 months (interquartile range, 6-16 months); 17% were sensitized, and 98% were virus positive. Current asthma (n = 37) at 8 years was divided into atopic (n = 19) and nonatopic (n = 18) asthma. The risk factors for current atopic asthma at study entry were sensitization (adjusted odds ratio [OR], 12; P < .001), eczema (adjusted OR, 4.8; P = .014), and wheezing with rhinovirus (adjusted OR, 5.0; P = .035). The risk factors for nonatopic asthma were the first severe respiratory syncytial virus/rhinovirus-negative wheezing episode (adjusted OR, 8.0; P = .001), first wheezing episode at age less than 12 months (adjusted OR, 7.3; P = .007), and parental smoking (adjusted OR, 3.8; P = .028). CONCLUSIONS: The data suggest diverse asthma phenotypes and mechanisms that can be predicted by using simple clinical markers at the time of the first severe wheezing episode. These findings are important for designing early intervention strategies for secondary prevention of asthma.

Rhinovirus species and clinical characteristics in the first wheezing episode in children.

The clinical data on the first wheezing episodes induced by different rhinovirus (RV) species are still limited. We aimed to investigate the prevalence of RV genotypes, sensitization status, and clinical characteristics of patients having a respiratory infection caused by either different RV species or other respiratory viruses. The study enrolled 111 patients (aged 3-23 months, 79% hospitalized, 76% with RV infection) with the first wheezing episode. RV-specific sequences were identified by partial sequencing of VP4/VP2 and 5' non-coding regions with 80% success rate. The investigated clinical and laboratory variables included atopic characteristics and illness severity, parental atopic illnesses, and parental smoking. Of the study children, 56% percent had >1 atopic characteristic (atopy, eczema and/or blood eosinophil count >0.4 × 109 /L) and 23% were sensitised to allergens. RV-C was detected in 58% of RV positive samples, followed by RV-A (20%) and RV-B (1.2%). Children with RV-A and RV-C induced wheezing were older (P = 0.014) and had more atopic characteristics (P = 0.001) than those with non-RV. RV-A and RV-C illnesses had shorter duration of preadmission symptoms and required more bronchodilator use at the ward than non-RV illnesses (both P < 0.05, respectively). RV-C is the most common cause of severe early wheezing. Atopic and illness severity features are associated with children having RV-A or RV-C induced first wheezing episode rather than with children having a non-RV induced wheezing. J. Med. Virol. 88:2059-2068, 2016. © 2016 Wiley Periodicals, Inc.

The first wheezing episode: respiratory virus etiology, atopic characteristics, and illness severity.

BACKGROUND: Susceptibility to early rhinovirus-induced wheezing has been recognized as an important risk factor for childhood asthma, but data on the first wheezing episode are limited. The aim of this selected population study was to investigate virus etiology, atopic characteristics, and illness severity, as well as their interrelation, among first-time wheezing children. METHODS: We studied 111 first-time wheezing children aged between 3 and 23 months (88/23 in-/outpatients). The investigated factors included atopy, food, perennial and aeroallergen sensitization, eczema, atopic eczema, elevated blood eosinophil count, and parental allergic rhinitis, asthma, and smoking. Nasopharyngeal aspirates were analyzed for adenovirus, coronaviruses, enteroviruses, bocavirus-1 (also serologically confirmed), influenza viruses, metapneumovirus, parainfluenza viruses, rhinovirus, and respiratory syncytial virus using PCR methods. RESULTS: The mean age of the study patients was 12 months (standard deviation 6.0). Atopic characteristics could be found in 56%, atopic eczema in 16%, and sensitization in 23% of the cases. In all samples (100%), ≥1 viruses were detected as follows: rhinovirus (76%), respiratory syncytial virus (29%), bocavirus (18%, acute infections), and other viruses <10% each. Virus coinfections occurred in 38% of the children. Rhinovirus infection was positively associated with age, blood eosinophil count, eczema, and duration of cough, as well as parental allergic rhinitis and smoking but negatively associated with virus coinfection (all p < 0.05). CONCLUSIONS: A respiratory virus infection can be detected in all first-time wheezing children. Rhinovirus dominated the findings and was linked to atopic characteristics, prolonged cough, and parental smoking.

Novel human gammapapillomavirus species in a nasal swab.

A divergent human gammapapillomavirus (γ-HPV) genome in a nasal swab from an elderly Finnish patient with respiratory symptoms was genetically characterized. The L1 gene of HPV-Fin864 shared <70% nucleotide identity to other reported γ-HPV genomes, provisionally qualifying it as a new species in the Gammapapillomavirus genus.

Merkel cell polyomavirus and trichodysplasia spinulosa-associated polyomavirus DNAs and antibodies in blood among the elderly.

BACKGROUND: Merkel cell polyomavirus (MCPyV) and trichodysplasia spinulosa-associated polyomavirus (TSPyV) are recently found pathogens causing two rare skin disorders, Merkel cell carcinoma (MCC) and trichodysplasia spinulosa (TS). MCC is proportionally common in the elderly and most often is associated with immunosuppression. TS is a folliculocentric infection seen in patients in an immunocompromised state. Little or no baseline information exists, however, on the prevalences of these two viruses among the elderly. Epidemiologic data on this population could help in understanding their natural biology. We wished to determine the occurrences and blood levels of MCPyV and TSPyV DNAs among the elderly and any association between the prevalences of their corresponding antiviral IgG antibodies. METHODS: From 394 hospitalized elderly individuals (age ≥65 years) with respiratory symptoms, cardiovascular, and other diseases, we studied 621 serum samples by four different real-time quantitative (q) PCRs, two for the DNAs of MCPyV and two for TSPyV. The IgG antibodies for both viruses among 481 serum samples of 326 subjects were measured with enzyme immunoassays (EIAs), using as antigen recombinant virus-like particles (VLPs). RESULTS: Of the 394 patients, 39 (9.9%) were positive at least once for MCPyV DNA by the LT PCR, and 33 (8.4%) by the VP1 PCR, while 6 (1.5%) were positive by both PCR assays. In general, the viral DNA copy numbers were low. In sharp contrast, no TSPyV DNA was detectable with qPCRs for the corresponding genomic regions. The IgG seroprevalence of MCPyV was 59.6% and of TSPyV, 67.3%. CONCLUSIONS: MCPyV DNA, unlike TSPyV DNA, occurs in low copy number in serum samples from a notable proportion of aging individuals. Whether this reflects enhanced viral replication possibly due to waning immune surveillance, and is associated with increased MCC risk, deserves exploration.

New respiratory viral infections.

PURPOSE OF REVIEW: The first era in the discoveries of respiratory viruses occured between 1933 and 1965 when influenza virus, enteroviruses, adenovirus, respiratory syncytial virus, rhinovirus, parainfluenza virus and coronavirus (CoV) were found by virus culture. In the 1990s, the development of high throughput viral detection and diagnostics instruments increased diagnostic sensitivity and enabled the search for new viruses. This article briefly reviews the clinical significance of newly discovered respiratory viruses. RECENT FINDINGS: In 2001, the second era in the discoveries of respiratory viruses began, and several new respiratory viruses and their subgroups have been found: human metapneumovirus, CoVs NL63 and HKU1, human bocavirus and human rhinovirus C and D groups. SUMMARY: Currently, a viral cause of pediatric respiratory illness is identifiable in up to 95% of cases, but the detection rates decrease steadily by age, to 30-40% in the elderly. The new viruses cause respiratory illnesses such as common cold, bronchitis, bronchiolitis, exacerbations of asthma and chronic obstructive pulmonary disease and pneumonia. Rarely, acute respiratory failure may occur. The clinical role of other new viruses, KI and WU polyomaviruses and the torque teno virus, as respiratory pathogens is not clear.

Induction and maintenance of allergen-specific FOXP3+ Treg cells in human tonsils as potential first-line organs of oral tolerance.

BACKGROUND: Tonsils are strategically located in the gateway of both alimentary and respiratory tracts representing the first contact point of food and aeroallergens with the immune system. Tonsillectomy removes only the palatine tonsils and sometimes adenoids. Lingual tonsil is anatomically big and remains lifelong intact. OBJECTIVE: The aim of this study was to demonstrate cellular and molecular mechanisms of oral tolerance induction to food and aeroallergens in human tonsils. METHODS: Tonsil allergen-specific FOXP3(+) regulatory T (Treg) cells, plasmacytoid dendritic cells (pDCs), and myeloid dendritic cells were characterized by flow cytometry and suppressive assays. Intracellular staining, [(3)H]-thymidine incorporation, and carboxy-fluorescein succinimidyl ester dilution experiments were performed. Tonsil biopsies were analyzed by confocal microscopy. RESULTS: CD4(+)FOXP3(+) Treg cells and pDCs constitute important T- and dendritic cell-compartments in palatine and lingual tonsils. Tonsil pDCs have the ability to generate functional CD4(+)CD25(+)CD127(-)FOXP3(+) Treg cells with suppressive property from naive T cells. CD4(+)FOXP3(+) Treg cells proliferate and colocalize with pDCs in vivo in T-cell areas of lingual and palatine tonsils. Tonsil T cells did not proliferate to common food and aeroallergens. Depletion of FOXP3(+) Treg cells enables the allergen-induced proliferation of tonsil T cells, indicating an active role of Treg cells in allergen-specific T-cell unresponsiveness. High numbers of major birch pollen allergen, Bet v 1-specific CD4(+)FOXP3(+) Treg cells, are identified in human tonsils compared with peripheral blood. A positive correlation between the percentages of FOXP3(+) Treg cells and pDCs is observed in tonsils from nonatopic individuals. CONCLUSION: Functional allergen-specific Treg cells are identified both in lingual and in palatine tonsils.

Seroepidemiology of the newly found trichodysplasia spinulosa-associated polyomavirus.

Trichodysplasia spinulosa (TS)-associated polyomavirus (TSV) was recently (in 2010) discovered in TS lesions. To investigate the seroprevalence and primary exposure time of this virus, we set up a virus protein (VP1) viruslike particle (VLP)-based immunoglobulin G enzyme immunoassay. The seroprevalence of TSV was 5%, among children aged 1-4 years, rising to 48% at 6-10 years, and 70% among 149 adults. The TSV antibodies did not cross-react with corresponding Merkel cell polyomavirus VLPs, and their reactivity appeared conformational. TSV circulates widely in the human population and primary exposure is extensive in childhood, beginning at age 1-2 years.

New respiratory viruses and the elderly.

The diagnostics of respiratory viral infections has improved markedly during the last 15 years with the development of PCR techniques. Since 1997, several new respiratory viruses and their subgroups have been discovered: influenza A viruses H5N1 and H1N1, human metapneumovirus, coronaviruses SARS, NL63 and HKU1, human bocavirus, human rhinoviruses C and D and potential respiratory pathogens, the KI and WU polyomaviruses and the torque teno virus. The detection of previously known viruses has also improved. Currently, a viral cause of respiratory illness is almost exclusively identifiable in children, but in the elderly, the detection rates of a viral etiology are below 40%, and this holds also true for exacerbations of chronic respiratory illnesses. The new viruses cause respiratory symptoms like the common cold, cough, bronchitis, bronchiolitis, exacerbations of asthma and chronic obstructive pulmonary disease and pneumonia. Acute respiratory failure may occur. These viruses are distributed throughout the globe and affect people of all ages. Data regarding these viruses and the elderly are scarce. This review introduces these new viruses and reviews their clinical significance, especially with regard to the elderly population.

Serological evidence of Merkel cell polyomavirus primary infections in childhood.

BACKGROUND: Merkel cell polyomavirus (MCPyV) was identified newly (2008) and is believed to be an etiologic factor of Merkel cell carcinoma (MCC). Recent molecular and serological data suggest that MCPyV infection is common in the general population. OBJECTIVES: The aim of this study was to investigate the age of primary exposure to MCPyV. STUDY DESIGN: A MCPyV-IgG EIA was developed using the MCPyV major capsid protein VP1 expressed and self-assembled into virus-like particles (VLPs) in insect cells. The assay was used to detect serum IgG antibodies in two groups of children. Group 1 comprised paired and 5-8 year follow-up sera from 217 children (3-13 years) with acute lower respiratory tract infection. Group 2 comprised sera from 158 children (1-4 years) with otitis media; 86 children underwent adenoidectomy and 72 did not, whereafter follow-up sera were obtained 3 years later. RESULT: The prevalence of MCPyV-IgG was 9% at 1-4 years, and increased to 35% at 4-13 years among subjects from Group 1, with a 33% seroconversion rate during 5-8 years. Among Group 2, the seroconversion rate was 16% during 3 years. The IgG prevalence at 4-7 years as well as the IgG levels showed an apparent gender difference, with male preponderance prevailing among the children without adenoidectomy. CONCLUSION: MCPyV primary infections occur ubiquitously in childhood, and the first exposure takes place at young age. The serology showed no evidence for a causative role of MCPyV in lower respiratory tract infection manifesting as acute wheezing, but was compatible with the notion of MCPyV persistence in tonsils.

Expression and serological characterization of polyomavirus WUPyV and KIPyV structural proteins.

The polyomaviruses WUPyV and KIPyV were recently discovered. We expressed their structural proteins VP1, VP2, and VP3, and the corresponding proteins of BKV and JCV, for immunoblotting of IgG antibodies from 115 wheezing young children and 25 asymptomatic adults. Furthermore, nasopharyngeal aspirates (NPA) and sera from the children were examined by PCR for viral DNA. The overlapping minor proteins VP2 and VP3 of WUPyV and KIPyV were more reactive in immunoblots than the major protein VP1; of 100 NPA PCR-negative wheezing children aged < or = 4 y, 31 (31%) and 31 (31%) were positive for WUPyV and KIPyV VP2/VP3, compared to only 3 (3%) and 5 (5%) for VP1, respectively. For comparison, the respective WUPyV and KIPyV IgG seroprevalences as determined by immunofluorescence assay (IFA) with nondenatured VP1 were 80% and 54%, respectively, among 50 NPA PCR-negative children aged < or = 2 y. This difference shows the importance of conformational VP1 antigenicity. Of the 25 adults, 52% and 68% were IgG-positive in immunoblots for VP2/VP3 of WUPyV and KIPyV, and 8% and 12% were for VP1, respectively. Of the 192 NPA samples studied by PCR, 7 (3.6%) were positive for WUPyV, and 3 (1.5%) were positive for KIPyV DNA. Unlike the NPA samples, none of the corresponding 443 sera contained WUPyV or KIPyV DNA. Together with the high VP2/VP3 IgG prevalence, this points to a paucity or brevity of KIPyV and WUPyV viremias among immunocompetent children. Our results indicate the significance of protein conformation in immunoreactivity of VP1, and show the antigenic importance of the WUPyV and KIPyV minor proteins VP2 and VP3. The high and rapidly increasing IgG prevalence rates observed in this study for WUPyV and KIPyV support the notion that these novel polyomaviruses are widespread and are acquired early in childhood.

Merkel cell polyomavirus DNA in tumor-free tonsillar tissues and upper respiratory tract samples: implications for respiratory transmission and latency.

BACKGROUND: Merkel cell polyomavirus (MCPyV) was discovered recently. It is considered a potential causative agent of Merkel cell carcinoma, a life-threatening skin cancer. OBJECTIVES: To study the prevalence of MCPyV in a large number of clinical samples of various types. Most of the samples were examined also for the other newly found polyomaviruses KI (KIPyV) and WU (WUPyV). STUDY DESIGN: Altogether 1390 samples from immunocompetent or immunocompromised patients, including (i) tonsillar tissues and sera from tonsillectomy patients; (ii) nasopharyngeal aspirates (NPAs) and sera from wheezing children and (iii) nasal swabs, sera and stools from febrile leukemic children were studied for MCPyV. The tonsils, nasal swabs and stools were also studied for KIPyV and WUPyV. RESULTS: MCPyV DNA was detected in 14 samples altogether; 8 of 229 (3.5%) tonsillar tissues, 3 of 140 (2.1%) NPAs, 2 of 106 (1.9%) nasal swabs and 1 of 840 (0.1%) sera. WUPyV and KIPyV were detected in 5 (2.2%) and 0 tonsils, 1 (0.9%) and 4 (3.8%) nasal swabs and 0 and 2 (2.7%) fecal samples, respectively. The patients carrying in tonsils MCPyV were of significantly higher age (median 42years) than those carrying WUPyV (4years, p<0.001). CONCLUSIONS: MCPyV DNA occurs in tonsils more frequently in adults than in children. By contrast, WUPyV DNA is found preferentially in children. MCPyV occurs also in nasal swabs and NPAs, in a frequency similar to that of KIPyV and WUPyV. The tonsil may be an initial site of WUPyV infection and a site of MCPyV persistence.